Go to the Quick Item Center, select the item that has been checked out and click "Check-in"

You will be taken to the following overlay where you can cross-check and add additional information regarding the check-in. To set the return time and location, click "Field Settings"

Change the "Return Location Type" and "Return Date Type" to "Custom Location" and "Custom Date" if you want to choose a location and date

Once you have filled in all the details, click "Check-in"

The following message will appear telling you that the item has been checked-in

How to Perform Quick Check-in